Precisely what do 净入学率 (~"net enrollment rate") and 毛入学率 (~"gross enrollment rate") mean?

I'm reading about literacy in China, and encounter the terms 净入学率 and 毛入学率, but I'm unclear on their precise meaning:

CC-CEDICT: 净 (jìng​) ... / net (income, exports etc) / ...
CC-CEDICT: 毛 (máo) ... / raw / ...
CC-CEDICT: 入学率 (rù​xué​lǜ​) percentage of children who enter school

The above seem to be the closest relevant definition. Putting the terms into Youdao gives "net enrollment rate" and "gross enrollment rate". I have no idea what the difference here is.

Moreover this news article lists a 毛入学率 of 102.5%, which sounds mathematically impossible.

Question: Precisely what do 净入学率 (~"net enrollment rate") and 毛入学率 (~"gross enrollment rate") mean?

• Gross - 总量, 总额 (n); 总的 (adj). 毛 - hair, fur, mane. The gross enrollment rate should be 总入学率, I've never heard of 毛入学率, but it might be defined in China with special meaning so that the gross rate can be > 100%.
– r13
Aug 24 '21 at 0:30
– r13
Aug 24 '21 at 0:48
• From the article cited above, 毛利率 ＝（營業收入－營業成本）／營業收入 x 100%, we can rewrite as 毛入学率 = (現下入学人數 - 過去入学人數)/現下入学人數 x 100%, since typically the result in ( ) will be less than the denominator unless the past number of enrolled student is negative, the listed rate does not make sense.
– r13
Aug 24 '21 at 1:18
• Okay, it can make sense if 毛入学率 is defined as the "net growth rate" of student enrollment, 毛入学率 = (現下入学人數 - 過去入学人數)/**過去入学人數** x 100%, so the result can be greater than 100%.
– r13
Aug 24 '21 at 1:46
• Wouldn't a Baidu search answer the question? It's just a way that Government measures the enrollment rate.
– dan
Aug 24 '21 at 5:26

$\dpi{120}&space;\fn_cm&space;\frac{\textrm{number&space;of&space;lower&space;secondary&space;school&space;students&space;regardless&space;of&space;their&space;ages}}{\textrm{population&space;aged&space;from&space;13&space;to&space;15&space;years&space;old}}$ × 100%