The phrase 'statistics say' is correct and usable in written English. You can use it when you are referencing statistics or data that has been compiled about a particular subject. For example: "Statistics say that the average person will spend seven hours a day on their phone next year.".
The statistics say otherwise.
The statistics say it all.
Statistics say he is right.
New York is safer now, statistics say.
I don't care what the statistics say".
Those statistics say plenty about the Jaguars.
Two sets of statistics say it all.
Being a terminologist, I care about word choice. Ludwig simply helps me pick the best words for any translation. Five stars!
Maria Pia Montoro
Terminologist and Q/A Analyst @ Translation Centre for the Bodies of the European Union