FXStreet (Edinburgh) - The US Dollar Index, which tracks the greenback vs. its main competitors, has started the week on a firm note, advancing above the 99.00 mark. US Dollar supported in narrow trade The index is trading a narrow 20-pip range for the time being, amidst a low volatility environment in response to the observance of the Martin Luther King holiday in the US. The greenback remains well supported in the area of 99.00 the figure, reverting last Friday’s drop to the mid-98.00s following the miserable prints from the US calendar, where retail sales have disappointed expectations during December. In the very near term, Chinese Q4 GDP figures are expected during the Asian session tomorrow, while developments in crude oil prices will also contribute to the market sentiment. US Dollar significant levels As of writing the US Dollar Index is up 0.12% at 99.09 with the next hurdle at 99.73 (high Jan.6) followed by 100.00 (psychological level) and then 100.60 (2015 high Dec.3). On the other hand, a breach of 98.14 (low Jan.8) would open the door to 97.48 (100-day sma) and finally 97.21 (50% Fibo of 93.82-100.60). For more information, read our latest forex news.