Hi there

This is how my dataset looks. There are 1,845,832 observations in it.

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input long(yearmonth businesspartner) float netnewmoney
201201 1234    0
201202 1234  150
201203 1234  240
201204 1234    0
201205 1234  120
201206 1234  240
201207 1234  120
201208 1234  120
201209 1234    0
201210 1234  160
201211 1234  390
201212 1234  160
201301 1234    0
201302 1234  160
201303 1234  200
201304 1234    0
201305 1234  400
201306 1234    0
201307 1234  400
201308 1234  500
201309 1234    0
201310 1234  200
201311 1234  400
201312 1234  200
201401 1234  200
201402 1234  200
201403 1234    0
201404 1234  200
201405 1234  400
201406 1234    0
201407 1234  400
201408 1234    0
201409 1234  200
201410 1234  400
201411 1234    0
201412 1234  400
201501 1234  200
201502 1234  200
201503 1234    0
201504 1234  200
201505 1234  200
201506 1234  200
201507 1234  400
201508 1234    0
201509 1234  200
201510 1234  400
201511 1234    0
201512 1234  400
201601 1234    0
201602 1234  200
201603 1234  200
201604 1234  400
201605 1234    0
201606 1234    0
201607 1234  400
201608 1234    0
201609 1234  400
201610 1234    0
201611 1234  300
201612 1234  600
201701 1234    0
201702 1234  300
201703 1234  200
201704 1234    0
201705 1234  100
201706 1234  100
201707 1234  200
201708 1234    0
201709 1234  400
201710 1234    0
201711 1234  200
201712 1234  400
201801 1234    0
201802 1234  400
201803 1234  700
201804 1234    0
201805 1234  300
201806 1234  600
201201 5678    0
201202 5678    0
201203 5678 3000
201204 5678    0
201205 5678 2000
201206 5678    0
201207 5678    0
201208 5678    0
201209 5678    0
201210 5678    0
201211 5678    0
201212 5678    0
201301 5678    0
201302 5678    0
201303 5678    0
201304 5678    0
201305 5678    0
201306 5678    0
201307 5678    0
201308 5678    0
201309 5678    0
201310 5678    0
end
As you can see it is monthly data of new deposits by customers.

I would now like to generate a variable that gives me the annual deposits. So a sum of these monthly deposits for each year and each customer.

Thanks for the help