recently my site suddenly down to 500+ position in google serp for all keywords. after several days, my site go where it was before. i know the similar thing happen to lots of sites because google update.but the more interested: my site contine to up for all of keywords. one of them go to first page. so i wanna know if the same thing also happen to other sites?(your site contine to up for some of keywords without doing something - for example:backlinks)