What determines your level in the "The Joker’s Carnival" map?

In this challenge map, is your level raised based on the score you're getting (thus making it more important to make the most out of each opponent) or is it raised based on how many opponents you take out (thus making it more important to finish opponents quickly)?

Note: Joker's Carnival is a combat challenge map from the DLC "Challenge Map Pack".

I think it might actually be the number of "landed blows" without taking a hit; if I do nothing but counter, I still start rising up the levels, despite not actually scoring any points. The first level seems to kick in after 10 hits, whether or not they form part of the same combo.

EDIT TO ADD: In fact, I am now all but certain that the level is based on the number of blows landed without being hit, with anything that increases the combo counter by more than one (Critical Hits, Blade Counters, Multiple Foe Counters) likewise applying for the level. I have tested multiple ways to unlock Level 1, and it's always after 10 strikes, whether chained in one combo, doing nothing but counter moves (and thus not scoring any points as you don't score anything for counters until you strike), or even punching and running around for the combo to end before punching someone again.

2nd EDIT: I believe the unlocking of each level to be:

• Level 1 10 strikes
• Level 2 25 strikes
• Level 3 50 strikes
• Level 4 85 strikes
• Level 5 120 strikes
• Level 6 165 strikes
• Max Gauge Bonus 220 strikes

Just like all of the other combat maps, it's based on how well you perform in combat, the only difference is that there's a timer, and constantly spawning enemies, instead of there being a set amount of enemies and no timer.

Your level, which you can use to "bank" increases based on your score since the last time you were hit by an enemy, or since you last banked.

Since it's based on how well you've been doing without being hit, it doesn't really matter whether you choose to take out as many enemies as you can the quickest, or if you choose to make the most out of each enemy. Just do whatever lets you build your points up the fastest.

I personally find it fairly easy to vary the combat while still taking enemies out quickly.

Just build up your combo and use both quickfire gadgets and special moves to get multipliers that will increase your score dramatically.

Levels are unlocked incrementally starting with level 1 at 1000 points, and increasing from there (Level 2 is either 2000, or 5000, I can't exactly remember).

A nice tip to get the three medals: Once you take down about ten henchmen (however many hits that is) at level six, you get a 1,000,000 point boost automatically.