If I remember right 1.025 is the average of surface salinity, but what ocean, it's lattitude, and depth, and temperature affect the range. A lot of oceans seem to be over 1.030 . There is salinity maps out there by NOAA I believe updated each year.
I keep mine at 1.026 but keeping in mind i tend to get a lot of salt creep, and evap so there is always swings. I've seen 1.035 in my tanks before and down to 1.019, usually in winter months. I've always been a believer salinity swings with observation help condition corals over time to be more forgiving, but thats only my hypothesis. I haven't done a water change since the last week of March, and swear it has helped, though calcium and Iodine needed to be supplemented.