Quoting Wikipedia's source, Forbes estimated her donations were $120 million to date in 2012. However, she co-founded her own charity in 2005, of which she is the president, and I suspect most of it has been donated in that direction.

Personally, I'm always dubious of the rich and famous genuinely finding unmet cases for charitable organisations. Especially when they've made a fortune outsourcing being morally dubious to others - she can save children because others are paying her to be allowed to sell low quality merchandise almost certainly made in exploitative conditions.

She's not alone, there's many more e.g. Messi donating lots to children's cause through his own charitable organisation after gladly being a global ambassador for unhealthy snacks targeted at children.

During feudalism the rich donated a far larger percent of their assets. The trend has been that the rich donate a smaller percent since then

Are you counting tithes as donations?

Tithe/charity/donations/taxes. It's fungible from a socio economic perspective.

Rowling made a lot of her money from books, which would mostly be printed by adults in the country they are published in. Also films, filmed in the UK.

That's a long way from advertising unhealthy snacks.

Lego isn't made in dubious conditions, so for toys she's already above average.