So… it… depends a bit on what their unit of measure is, but we could derive it.
my money would be on a timestamp (seconds since epoch). but lets see if we put it in terms of days:
We take for granted that our domain starts at 0. We can arbitrarily say that January 1, 2016 = 0.
If January 1, 2016 is 0, what is January 1, 2017? Well 2016 was a leap year, so given the previous value is 0, January 1, 2017 would be 366.
The range is specified to be 0…700.
So we have two points: 0,0 and 366,700.
It may have been a while since i did line calculations, but the slope of the line would be 700/366 ((y2-y1)/(x2-x1)), or 1.912568306.
Our Y-intercept is 0 (because we have a point at 0,0), so the equation y = mx + b of our line is 1.912568306x + 0, or just 1.912568306x.
if we take the date provided, July 1st, and translate it to our days-since system, it would be 182. If we put 182 into the equation for our line, we get 1.912568306 * 182 = 348.087431692.