"Reach a level" means "get to that level by increasing the level", unless other words mean "lowering".Do we say "reach a standard of living"?
Was it lower until recently? If not, don't use "reach".No actually we are talking here about a low and very poor standard of living!
"People have" means this is the level.We should know the reason why the Yemeni people have
reachedthis standard of living.