The following charts and narrative are from Kohls Corporations Form 10-K for FYE February, 2019.

Our Kohl's stores and website sell moderately-priced proprietary and national brand apparel, footwear, accessories, beauty and home products. Our merchandise mix includes both national brands and proprietary brands that are available only at Kohl's. Our proprietary portfolio includes well-known established private brands such as Apt. 9, Croft & Barrow, Jumping Beans, SO and Sonoma Goods for Life and exclusive brands that are developed and marketed through agreements with nationally-recognized brands such as Food Network, LC Lauren Conrad, Elle and Simply Vera Vera Wang. National brands generally have higher selling prices, but lower gross margins, than proprietary brands. The following summarize our sales penetration by brand type over the last three years:

Looking at the chart and narrative, what has happened to the mix of national brands and proprietary brands over time?