...but as the Guardian article says, over 80% is, and those are the bricks you probably think of when hearing "LEGO" - the remainder are elements that are trans

...but as the Guardian article says, over 80% is, and those are the bricks you probably think of when hearing "LEGO" - the remainder are elements that are transparent, bendy, have to be especially durable or have other special requirements. The article you linked also includes several "historic" plastic materials that aren't used anymore.