年份的月数 计算出 (11838)

C2:P15{=TEXT(INDEX(FREQUENCY(EOMONTH(DATE(C$1,ROW($1:$12),),1),EOMONTH(N(IF({1},$A2:$B2*1)),{0,-1})),2),"0;;")

另解=TEXT(SUMPRODUCT(N(YEAR(EOMONTH($A2,ROW(INDIRECT("1:"&DATEDIF($A2,$B2,"M")))))=C$1)),"0;;")