It is difficult to diagnose issues like these without more detailed information and photos, or even samples of the problem. Because of this, we can only provide the likelihood of certain issues.

Fireblight has been a big issue this year. It is a bacterial disease that is very destructive and made worse in some years based on weather conditions favorable to this disease. Here is a very good article and the CSU Fact Sheet for treatment:

http://csuhort.blogspot.com/2018/06/fireblight-running-rampant.html

http://extension.colostate.edu/topic-areas/yard-garden/fire-blight-2-907/

It appears there may be something more cumulative or long term if a homeowner’s description includes 'increasingly' or 'each year'. The polar vortex of November 2014 left many trees in a state of trauma. The link below is an article written in 2016 — two years after the polar vortex. Even in 2018, we see the continuing injury left by this historic weather event with damaged and missing or sloughing bark, dead & dried up limbs and/or branches. There is no treatment for this, but here is more information:

http://csuhort.blogspot.com/2016/07/a-lost-hope.html

http://csuhort.blogspot.com/2015/04/frozen-iii-cold-snap-story-continues.html

http://csuhort.blogspot.com/2014/12/frozen-2-tree-edition.html

Damaged or missing upper branch bark can also be indicative of anything from hail damage to squirrel feeding.

Cytospora canker can cause branch dieback on apple trees. More information on symptoms and treatment at this link:

http://extension.colostate.edu/topic-areas/agriculture/cytospora-canker-in-tree-fruit-crops-2-953/

It appears that your tree is healthy enough to produce an abundant and healthy crop. Keeping fruit trees healthy includes:

• Not planting the tree in the lawn as lawn fertilization and watering is more than what is needed by fruit trees.

• Use organic mulch (wood chips, straw, pine needles, etc.) over the rooting area to keep soil cool, moist and promote a good root zone environment.

• In February-March, prune to a low, open center so that there is good sunlight penetration into all parts of the canopy. Avoid pruning out short stubby twigs on apples; these "spurs" bear most fruit. Spray pruning blades with Lysol between each cut, especially when pruning apples.

• Lightly fertilize in late April or May. Use a granular fertilizer applied to the rooting area that is watered after the application. Excessive nitrogen fertilizer can promote fireblight disease in apples.

If the above information is not helpful, consider contacting an arborist to look at the tree and assess the overall health and any treatment that might be necessary.

http://www.treesaregood.org/findanarborist