Hello everbody!

I am currently working on my thesis and do not know how to generate cumulative GDP variables per year per country. I would need GDPcurrentUSmillionsseasa in Q2 to be the number from Q2&Q1, for Q3 all previous, but only for each specific year and country. As of now, the values depicted only reflect the values within a quarter (and are not accumulated).
In order to linearly interpolate from quarter to month, I would need the cumulative GDP figures.

Does anybody know how to do this?

Any small hint is appreciated.

Thank you very much!


Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input str4 Year str6 Time float countryid str3 CountryCode double GDPcurrentUSmillionsseasa
"2000" "2000Q1" 8 "ARG" 80437.2008416527
"2000" "2000Q2" 8 "ARG" 78528.0824320725
"2000" "2000Q3" 8 "ARG" 78769.9006895087
"2000" "2000Q4" 8 "ARG" 80285.4740107538
"2001" "2001Q1" 8 "ARG" 78744.0942739926
"2001" "2001Q2" 8 "ARG" 76749.4901212289
"2001" "2001Q3" 8 "ARG" 74341.3501456239
"2001" "2001Q4" 8 "ARG" 70956.3874655378
"2002" "2002Q1" 8 "ARG" 36830.3842177286
"2002" "2002Q2" 8 "ARG" 27211.4443886902
"2002" "2002Q3" 8 "ARG" 25380.2537402623
"2002" "2002Q4" 8 "ARG" 27029.8937608728
"2003" "2003Q1" 8 "ARG" 31007.2584011089
"2003" "2003Q2" 8 "ARG" 36729.9477676858
"2003" "2003Q3" 8 "ARG" 36432.1161813601
"2003" "2003Q4" 8 "ARG" 38852.1717719708
"2004" "2004Q1" 8 "ARG" 40178.7789622911
"2004" "2004Q2" 8 "ARG" 41063.1171238067
"2004" "2004Q3" 8 "ARG" 40940.8897185555
"2004" "2004Q4" 8 "ARG" 42818.1588750444
"2005" "2005Q1" 8 "ARG" 46077.2498559558
"2005" "2005Q2" 8 "ARG" 49154.2846049257
"2005" "2005Q3" 8 "ARG" 51363.9078509211
"2005" "2005Q4" 8 "ARG" 52698.5279903164
"2006" "2006Q1" 8 "ARG" 55209.2969189064
"2006" "2006Q2" 8 "ARG" 55863.1922350211
"2006" "2006Q3" 8 "ARG" 59344.4964046419
"2006" "2006Q4" 8 "ARG" 62450.5143493273
"2007" "2007Q1" 8 "ARG"  65613.974766014
"2007" "2007Q2" 8 "ARG" 69329.8863396363
"2007" "2007Q3" 8 "ARG" 73041.3878812713
"2007" "2007Q4" 8 "ARG" 79631.5928090261
"2008" "2008Q1" 8 "ARG" 85889.5277501459
"2008" "2008Q2" 8 "ARG" 92202.4147579751
"2008" "2008Q3" 8 "ARG" 97154.0720975794
"2008" "2008Q4" 8 "ARG" 88282.9783624023
"2009" "2009Q1" 8 "ARG" 82350.5350114808
"2009" "2009Q2" 8 "ARG" 79722.0482782542
"2009" "2009Q3" 8 "ARG" 82781.8817089798
"2009" "2009Q4" 8 "ARG" 89599.2297565583
"2010" "2010Q1" 8 "ARG" 96923.9090725865
"2010" "2010Q2" 8 "ARG" 102829.670741129
"2010" "2010Q3" 8 "ARG" 108496.070135516
"2010" "2010Q4" 8 "ARG" 115952.757973306
"2011" "2011Q1" 8 "ARG" 123306.912515801
"2011" "2011Q2" 8 "ARG" 130516.653871534
"2011" "2011Q3" 8 "ARG" 134838.957938279
"2011" "2011Q4" 8 "ARG" 138285.942871563
"2012" "2012Q1" 8 "ARG" 141371.458328581
"2012" "2012Q2" 8 "ARG" 141974.520471506
"2012" "2012Q3" 8 "ARG" 146409.840259834
"2012" "2012Q4" 8 "ARG" 149365.798287112
"2013" "2013Q1" 8 "ARG" 150738.348201882
"2013" "2013Q2" 8 "ARG" 153862.312397311
"2013" "2013Q3" 8 "ARG" 153385.610328411
"2013" "2013Q4" 8 "ARG" 152938.674270556
"2014" "2014Q1" 8 "ARG" 134552.315277504
"2014" "2014Q2" 8 "ARG" 138873.803339068
"2014" "2014Q3" 8 "ARG" 140727.051099311
"2014" "2014Q4" 8 "ARG" 148617.037496602
"2015" "2015Q1" 8 "ARG" 153221.558400471
"2015" "2015Q2" 8 "ARG" 158529.346422297
"2015" "2015Q3" 8 "ARG" 167239.614461165
"2015" "2015Q4" 8 "ARG" 163335.098277682
"2016" "2016Q1" 8 "ARG" 126498.372688993
"2016" "2016Q2" 8 "ARG" 141759.308130076
"2016" "2016Q3" 8 "ARG" 141873.556240002
"2016" "2016Q4" 8 "ARG"    146145.622024
"2017" "2017Q1" 8 "ARG" 153563.055838637
"2017" "2017Q2" 8 "ARG" 161793.727170131
"2017" "2017Q3" 8 "ARG" 159726.981122706
"2017" "2017Q4" 8 "ARG" 167816.580549218
"2018" "2018Q1" 8 "ARG" 161723.755433079
"2018" "2018Q2" 8 "ARG" 144347.187622073
"2018" "2018Q3" 8 "ARG" 116872.015271018
"2018" "2018Q4" 8 "ARG" 112359.102870314
"2019" "2019Q1" 8 "ARG" 116364.620835962
"2019" "2019Q2" 8 "ARG" 115398.941200056
"2019" "2019Q3" 8 "ARG" 109612.464935174
"2019" "2019Q4" 8 "ARG" 105311.217929914
"2020" "2020Q1" 8 "ARG" 107681.414847743
"2020" "2020Q2" 8 "ARG"                .
"2020" "2020Q3" 8 "ARG"                .
"2000" "2000Q1" 9 "ARM"  523.86502645952
"2000" "2000Q2" 9 "ARM"  563.51866929341
"2000" "2000Q3" 9 "ARM"  492.15712826561
"2000" "2000Q4" 9 "ARM"  525.78372691071
"2001" "2001Q1" 9 "ARM"  576.96941683174
"2001" "2001Q2" 9 "ARM"  593.15194396415
"2001" "2001Q3" 9 "ARM"  571.41525776956
"2001" "2001Q4" 9 "ARM"  581.77519111539
"2002" "2002Q1" 9 "ARM"  614.83928199611
"2002" "2002Q2" 9 "ARM"  597.40282593417
"2002" "2002Q3" 9 "ARM"  680.21255312218
"2002" "2002Q4" 9 "ARM"  677.78398891292
"2003" "2003Q1" 9 "ARM"  698.96121883268
"2003" "2003Q2" 9 "ARM"  731.65279640052
"2003" "2003Q3" 9 "ARM"  775.14751107883
"2003" "2003Q4" 9 "ARM"  837.50716052064
"2004" "2004Q1" 9 "ARM"  854.66169371591
end