Stops are the most common manner of articulation at all stages and are produced more often than they are present in the target words at around 18 months. Gradually this frequency decreases to almost target-like frequency by around 27 months. The opposite process happens with fricatives, affricates, laterals and trills. Initially, the production of these phonemes is significantly less than what is found in the target words and the production continues to increases to target-like frequency. Alveolars and bilabials are the two most common places of articulation, with alveolar production steadily increasing after the first stage and bilabial production gently decreasing. Labiodental and postalveolar production increases throughout development, while velar production decreases.