想利用cfps数据库2010-2018年的数据，根据年份省份分组，统计各省每年适婚年龄（20-40）性别比
gen age_n  = inrange(age, 20,40), replace
tab gender, gen(male)

bys year province: egen male = count(male1) if age_n=1
bys year province: egen male = count(male2) if age_n=1
bys year province: gen sex_ratio = male/female

想是这么想的，但是报错
“. bys year province: egen male = count(male1) if age_n=1   
=exp not allowed”


想知道有什么办法可以实现呢？