Mobile banking ain’t growing like it used to.

A deep look mobile banking at the Big 3 banks — Bank of America, Wells Fargo & Co. and JPMorgan Chase & Co. — finds user growth easing. The banks had a total of 51.8 million mobile banking users at the end of last quarter, up from 49.7 million in the fourth quarter of 2014 and 43.9 million after 1Q 2014. That user total for last quarter represents growth rates of 4.15% quarter-over-quarter and 17.91% year-over-year.

Now, you may be thinking that 17.91% year-over-year growth sounds pretty darn good. Well, yes, that’s true, but consider this: the YOY growth rate for the Big 3 has slowed consistently from 1Q 2014, when the rate was 22.28%, through last quarter. Why? Because the raw number of users added per quarter is, well, bouncing along. Last quarter, about 2 million were added; the previous quarter 1.5 million; 3Q14 2.4 million — you get the picture (which happens to appear below).

Among the three banks, Bank of America is the laggard. Its YOY growth rate fell to 12.67% last quarter. It was 19.05% in the first quarter last year.

JPM, meanwhile, has kept its mobile user growth rate over 20% (it was actually 21.72% last quarter). The bank now has the largest number of mobile users at 19.96 million. If it hasn’t already done so, JPM will be the first bank in the US to cross the threshold of 20 million mobile users.