The IPA websites shows the following:
Active membership currently stands at 1798 of whom 328 are shown as unemployed. The breakdown of unemployed members by experience level is as follows:
300 hours 91
300-500 hours 45
500-1000 hours 48
1000-1500 hours 37
1500-2000 hours 23
2000-3000 hours 30
3000-5000 hours 21
5000 hours 33
It doesn't give a clue as to the overall total but gives some clues as to the distribution of experience.