How many symbols can I follow with Interactive Brokers?

Here is IB’s communique:
100 simultaneous market data lines may now be displayed in the Trader Workstation (and API clients) for free. Customers with greater than $800 USD (or equivalent) of commissions in a month will be provided with additional market data lines in the next month at the rate of 1 line for each $8 USD (or equivalent) of commissions above $800 USD (or equivalent).