Not bad efficiency numbers considering the returns are so high. Meanwhile, you might think that the lowest possible tax efficiency would come with a fund like a taxable money market, which paid out all its returns in the form of taxable income. But funds with very weak total returns, even if they don't pay out all that much income, can have much lower efficiencies. Something to keep in mind about a fund's past tax efficiency is unrealized gains - built up before a newer investor bought into a particular fund. A fund that has gone up a lot, but not distributed much, is holding a lot of securities with unrealized gains.
Index funds are a classic example.
If the fund ever sells those securities, it will realize those gains and have to distribute them to shareholders. In the next bear market, it's possible that enough investors will sell out of index funds that the funds will have to unload a lot of their stock holdings. So some of these usually very tax-efficient index options might have to make big capital gains distributions. This is not a reason to sell an index fund, but might give you a reason to consider newer funds that should distribute less without the previous gains. So now that April is here and taxes are due, it might be a good time for those in taxable accounts to check your fund's tax efficiency.