Practice
Fixing the pinky
Why the right pinky lags, and how to bring it up to the rest of the hand.
Look at the per-finger error chart on your stats page. Most typists have one finger doing twice as many errors as the others. It is usually the right pinky.
Why
The right pinky has the worst job in touch typing. It is the weakest finger. It is responsible for the most distant column of keys -- P, semicolon, slash, plus the Enter and right-Shift keys when those come up.
It also handles many of the closing-punctuation marks: colon, single-quote, double-quote, question mark. These are exactly the keys that show up at the ends of sentences, when your hands are already tired and your accuracy has been slipping for a paragraph.
The result is predictable. Average error rate on a typical typist's pinky column is two to three times the rate on the index column.
The fix
There is no shortcut. The pinky needs targeted practice. Three drills, one of them every other day, will close the gap in a few weeks.
Right pinky finger -- the dedicated drill. Six keys, no others. Run it for five minutes.
Punctuation drill -- forces shifts to the marks the pinky owns.
Quote-punctuation drill -- specifically trains the apostrophe-and-quote rhythm at the ends of sentences.
Form
Two technique notes that matter more than the drills.
Reach with the finger, not the hand. The pinky has the longest reach, but it should still be the part that moves. If you are tilting your wrist to the right to hit the semicolon, you are dragging the rest of the hand off the home row. You will lose your J anchor and your next several keys will be off.
The motion is: pinky stretches, hits, returns. Wrist still. Index finger still on J.
Use the right shift for capital letters on the left side of the keyboard. A common bad habit is to use the left shift for everything. If you are typing a capital A or capital S, the right pinky should be holding shift. If you are typing a capital P or capital L, the left pinky holds shift. The site of the shift press is always opposite to the letter.
This rule cuts your right pinky's per-keystroke load roughly in half on capitalized text.
Patience
The pinky takes longer to train than the rest of the hand because it gets fewer reps in normal typing. You have to deliberately drill it. Most typists who close the gap do so in three to six weeks of targeted practice, then maintain it with one drill a week.
There is nothing to be done about it being weaker. There is a lot to be done about it being slower than the other fingers, because slow comes from technique. Fix the technique and the pinky will sit at twice the error rate of the index finger -- which is the right ratio. It is a smaller finger. It should not be trying to keep up at the same rate.