How often do Spanish speakers in the United States end up forgetting Spanish?

An article here in Spanish today on the future of Spanish in the United States goes over some ground that we've seen before: in 2050 the US will have the largest Spanish-speaking population in the world, knowledge of Spanish will go from about 5.7% worldwide to about 10% by then. There is one number in the article that is new to me though:

Respecto de Estados Unidos, el académico explicó que si bien “el 23% de los inmigrados y exiliados ha perdido su lengua materna”, en la mayoría de los casos, “la lealtad lingüística es un hecho” y “encontramos situaciones bilingües perfectamente equilibradas”.

= "In the United States, though 23% of immigrants and exiles have lost their mother tongue, the majority of the time people are "loyal" to their language and perfect bilingualism is often encountered.

I assume this 23% is over a generation, but there is no source given and a quick search on Google doesn't turn one up. Then again, the article is a bit sloppy. It ends with:

...por ejemplo, si bien el 25% del mundo es hispanohablante, apenas el 5% de las páginas web están en español.

= "while 25% of the world speaks Spanish, just 5% of web sites are in Spanish." So let's hope that the percentage of people in the world that understand Spanish will increase to 10%, but 25% of the world understands Spanish.

?

Either that or it means "even if" 25% of the world speaks Spanish...but in that case it would make the 5% number meaningless as there is no way to predict how many pages on the internet would be in Spanish in such a hypothetical situation. Or perhaps I'm missing something.