Sugar is much less of a problem if you are also being very active on a daily basis. For example, your work contains physical component or maybe you are walking a lot.
So while the graph is showing dropping amount of sugar consumption, it is not taking account for also falling healthy limit of sugar consumption, ie. the fact that we should be eating even less overall given falling activity levels.
And this is especially true for kids whose activity levels fallen dramatically since smartphones.
I can tell that the same amount of sugar has much less effect on me since I lost weight and started running a lot every day. And I know this because I put on a continuous glucose monitor from time to time and can observe sugar spikes from foods to debug my diet.
You can learn a lot wearing CGM like the fact that my local Starbucks was serving me lactose-free milk regardless of what I ordered. You can tell lactose-free milk on a CGM because of a huge glucose spike. The reason? "Lactose free" is misleading. In reality they don't remove lactose. Lactose-free milk is obtained by adding to milk an enzyme that converts lactose to glucose and galactose which can be easily absorbed by the body and cause blood glucose spikes.