When Russia's natural gas-export monopoly Gazprom said over the weekend it may end discounts for Ukraine, unease rippled across the rest of Europe, too.

That's because about half of the Soviet-era pipelines that carry Russia's gas to Europe pass through Ukraine. And despite the European Union's goal to reduce dependence on Russian natural gas and increase energy independence, Gazprom's European market share actually increased last year, to 30 percent, a 20 percent increase from a year earlier.

Here's a visual:

Even Gazprom officials didn't expect to reach 30 percent market share in Europe until 2020. Lower gas production in Europe and higher consumption in Italy, the U.K. and Germany drove profits to Russia.

To increase energy independence, the European Union has a few options: use hydraulic fracturing technology to drill shale, make gas markets more open and competitive (Gazprom is facing possible antitrust charges from the EU) and consider renewable energy sources.

But if Russia did halt gas exports or hike prices, Norwegian and Algerian pipelines could fill demand to some of Europe, and tankers could increase shipments of liquified natural gas.