This doesn't include promos, but by a quick count it looks like standard currently has

35 Low Blocks
67 High Blocks

(And, 8 of Tekken's 13 low blocks are R/UR)

Now, in most fighting games low attacks are much tougher to block, because you need to do a crouching block or jump or something whereas high attacks are often blockable with a normal block. So personally I think this is kinda cool, as it adds a little bit more fighter-realism, and makes low attacks and high attacks different in a meaningful way. Like I said, it's just an observation, but for any who might not have noticed this yet it's certainly worth keeping in mind when choosing your attacks.

Although low blocks are more rare i feel that the majority of high/mid attackshave a higher base speed than low attacks?

My playgroup and I have figured out that low attacks real dam good as they may aswell be considered throws, when we use wonderwold warriors (the one tht can change zones) we always make the attack low.

And the majority of low attacks are pokes. Raging Gnome, Double Grounder Beta and Mighty Knee Strike are the only really beefy attacks coming from down low... and MKS is only 1spd lol.

Leg Slash and Alphard Maliki are the next biggest at 3L5 and 2L6 [throw], respectively. Only 4 difficulty!

Execution First Rite, Fire Shadow, Yi Shan's Leg Sweep, and Swing Kick are all 2~3 speed, 3 dmg. Razor's Bite is 4spd

Lowdown Neb starts at 5L1 and causes vit drain, so it has to be full-blocked for any effect.

aaand there's Ensnaring Sleeve, which is 1L2. :S

With the release of Tekken, there are some really powerful low attacks to contend with:

King's Reverse DDT

Wipe the Floor

Spinning Demon

As well as some other attacks that will no doubt see play:

Tandoya

Side Flop

I'd have to say that Spinning Demon is the most threatening though. You just need to look at Heihachi and Need to Destroy to find out why.

-Tinman

Yea there really isn't that many low attacks that are worth blocking. Not on their own anyway.

Most kill cards have been High attacks, and I think that influenced the spread of blocks on the cards. And juts not kill cards, alot of highly used attacks were or are High.

Feline Spike, Knight Breaker, Menuett Dance, Curse of the Ancient Mariner, Concealed Shallow Swipe, Kasumi Suzaku, 8th Bill, Bird of Prey, Drop Kick, Genkotsu Stamp, High Plasma Beam, Iori's Fireball, Kubi Ori, Midnight Launcher, Ryu's Tatsumaki (And it's replacement Messatsu-Gorasen), Overhand Throw, Roundhouse Kick, Shadow Banishment, Siegfried's Earth Divide, Spinning Beat, Twilight Embrace, Tiger Furry... heck even Bamboo Cutter is a High attack (yes, that one is for you... you know who you are.)

So yes, we need high blocks because well, people keep throwing High attacks at us.