Dear Statalist experts,
I have the following time series of the US population by city and state in 2010-2017.

They have the following shape:

city state y2010 y2011 y2012
"Abbot" "Maine" "714" 706 700

I need to transform these into the following panel:

city state population year
"Abbot" "Maine" "714" 2010
"Abbot" "Maine" 706 2011
"Abbot" "Maine" 700 2012
"Abbot" "Maine" 701 2013
"Abbot" "Maine" 702 2014
"Abbot" "Maine" 709 2015
"Abbot" "Maine" 703 2016
"Abbot" "Maine" 703 2017

"Acton" "Maine" 2447 2010
"Acton" "Maine" 2481 2011

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear

input str57 name str20 state str8 y2010 long(y2011 y2012 y2013 y2014 y2015 y2016 y2017)

"Abbot"                  "Maine"         "714"         706     702     698     692     684     682     678
"Abernathy"              "Texas"         "2805"       2833    2822    2798    2738    2724    2741    2735
"Abilene"                "Texas"         "117063"   118762  119853  119797  120648  121707  121883  122186
"Abington"               "Massachusetts" "15985"     16076   16095   16164   16230   16266   16335   16417
"Abrams"                 "Wisconsin"     "1856"       1859    1850    1852    1858    1860    1864    1871
"Acadia Parish"          "Louisiana"     "61773"     61865   61997   62299   62667   62679   62786   62559
"Ackerly"                "Texas"         "220"         219     219     225     228     230     229     228
"Ackley"                 "Iowa"          "1589"       1575    1573    1560    1558    1546    1537    1520
"Ackley"                 "Wisconsin"     "524"         520     517     512     509     503     505     508
"Acton"                  "Maine"         "2447"       2481    2497    2513    2539    2553    2567    2588
"Acton"                  "Massachusetts" "21924"     22274   22676   22928   23256   23488   23607   23716
"Acushnet"               "Massachusetts" "10303"     10304   10322   10346   10399   10453   10483   10520
"Acworth"                "New Hampshire" "891"         895     896     891     891     891     888     884
"Adair"                  "Iowa"          "781"         767     754     746     743     719     699     702
"Adams"                  "Massachusetts" "8485"       8426    8422    8381    8318    8238    8174    8120
Many thanks in advance.