early 1939 estimate by Nuyt:
37mm Pak: 8900 (8449 in August 1938- Fleischer)
75mm IG: 2300
15cm SiG: 250
7,5cm FK16: 298
7,7cm FK 96/16: 78
FK 16 n.A.: 130
FK 18: 0
10cm Kanone 17: 66 (incl 17/04)
10cm Kanone 18: 300-400
10,5cm lFh16: 980
10,5cm lFh18: 1300
15cm sFh13: 696 (incl sFH13/02)
15cm sFh18: 170?
15cm Kanone 16: 28
15cm Kanone 18: 0
Note that according to the Sturmvogel site 750 field arty pieces were produced in 1939 as well as 1700 at guns, 240 infantry guns. During the Polish campaign 195 pieces were lost (
http://www.mapleleafup.org/forums/showthread.php?t=3481&highlight=blitzkrieg)