You need to look at when the majors will be having retirements. It hasn't hit yet... when it does they will be hiring up regional pilots left and right because there are very few military pilots these days. And actually they will need more pilots than currently exist at the regionals. In other words, it's still early yet, but it won't be for long.

Here is the information for DAL --

Mandatory retirements:

2016: 99 (from 1 Sept to EOY)
2017: 308
2018: 403
2019: 468
2020: 553
2021: 767

Projected Retirement Numbers (Feb 2016):

2016: 189
2017: 267
2018: 377
2019: 471
2020: 566
2021: 772
2022: 830
2023: 790
2024: 791
2025: 711
2026: 608
2027: 513
2028: 507
2029: 511
2030: 541
2031: 476
2032: 424
2033: 356
2034: 302
2035: 260
2036: 256
2037: 227
2038: 203
2039: 159
2040: 178

SOURCE: Delta Air Lines | AirlinePilotCentral.com